My observation is that 1st class mail and Priority Mail packages take roughly twice as long as last year, or even early this year. Express Mail still meets its commitments. Weekly junk mail ALWAYS arrives on time. Anything else is a ****shoot. Magazines have never had a firm service guarantee, though the few I still get on paper usually arrive around the same week of the month. Magazine delays are often not on the USPS - most often, it's a production or delivery to the USPS delay which, obviously, affects when it'll be delivered. MR and Trains at the magazine rack in my local supermarket have widely variable availability times, too, so I'm not going to call delay a USPS bad without further review.

FWIW, all the delivery services are having their issues. As with USPS, the delay is not always on the service - late drop by the shipper is the problem more than half the time if tracking is to be believed. Still, FedEx has met its delivery day, to my location, precisely once in about 1/2 dozen shipments this year, and a couple of the misses were by over a week while in their system; I don't live in the boonies. UPS on the whole is the most consistent; few unexplained delays. Amazon - Prime used to be consistently 2 days, but about 6 months ago that went out the window and packages now take at least a week; the tracking often shows quite creative routing for generating delay. Staples is doing pretty good, though; they mostly use UPS, and for stuff that's normally in the store the "next day" promise (from a regional warehouse) is almost always met. Home Depot and Target and Walmart: if you can't pick it up at the store (they have curbside pickup for various values of curbside), expect at least a week, often 2, for delivery, and even things that are shown as in-stock at the store are often shipped instead of tagged for pickup.

Not all of this is Covid-related, though things have deteriorated since that became a thing. Most, I think, is just overload as more people shop online.